In general, headlamps are installed at a front side of a vehicle, and the vehicle travels in a state in which the headlamps installed at both sides of the front side of the vehicle are turned on because a visual range becomes significantly shorter when the vehicle travels at night than a visual range when the vehicle travels during the day time.
Meanwhile, a bulb, which serves as a light source, also generates electromagnetic waves when the bulb emits light. In a case in which the bulb is a high intensity discharge (HID) bulb, a magnitude of the electromagnetic waves, which are generated together with light, is increased together with intensity of light which is generated by high voltage to emit light with high intensity. In a case in which a magnitude of the electromagnetic wave generated from an optical system module is large when the optical system module is used as a headlamp for a vehicle, the electromagnetic wave, which leaks from the optical system module, interferes with an electronic control unit (ECU) of the vehicle, which causes various types of problems such as a problem that an engine is turned off while the vehicle travels, rattling of the engine, rpm instability, and instability of an instrument panel.
To solve the aforementioned problems, the headlamp for a vehicle in the related art is provided with an electromagnetic shield ring having a ring shape, but there are problems in that fixed costs are incurred due to a manufacturing method, and because the electromagnetic shield ring is assembled to the bulb by being fitted with the bulb, the electromagnetic shield ring is easily withdrawn when the bulb is replaced. In addition, a large number of ground contact points cannot be ensured due to the shape of the headlamp, and as a result, there is a limitation in blocking the electromagnetic wave.